Sharpness at 18mm

For this test, the Canon EF-M 18-150mm f/3.5-6.3 IS STM was mounted on a Canon EOS M5, which in turn was mounted on a sturdy tripod. Exposure delay mode was activated. Tonal and colour variances across the crops are due to changes in natural light during the session.

The full frame at 18mm

At 18mm, the centre of the frame is at its sharpest between f/4.0 and f/8.0. At f/11, there’s a tiny bit more softness, and more again from f/11 onwards. Images taken at f/16 and f/22 are soft due to diffraction, but it’s only particularly noticeable if you examine the centre of the image at 100%. This lens doesn’t have a particularly wide aperture capability, so there’s not a huge difference between sharpness in the centre and sharpness at the edges of the image.

The situation is similar across all of the different focal lengths, with a good degree of sharpness across the frame - especially if you’re looking at an image at normal printing or web reproduction sizes.

Aperture	Centre Crop	Edge Crop
f/3.5
f/4
f/5.6
f/8
f/11
f/16
f/22